A sliding door used as a side door of a van is opened or closed while being slid frontward and rearward along a rail of a vehicle panel.
FIG. 1 is a view showing a state in which a top rail, a bottom rail, and a center rail are mounted on a side outer panel according to the prior art; and FIG. 2 is an enlarged view of a center rail mounting part of FIG. 1.
A rail structure for a sliding door according to the prior art will be described with reference to FIGS. 1 and 2. The front, which is a position at which the sliding door is closed, of a side outer panel 10 is installed with a top rail 70 and a bottom rail 80, and a side surface of the side outer panel 10 is installed with a center rail 90 lengthily extending from the position at which the sliding door is closed to the rear of the side outer panel 10.
The top rail 70, the bottom rail 80, and the center rail 90 have a top roller 75, a bottom roller 85, and a center roller 95 slidably coupled thereto, respectively. The top roller 75, the bottom roller 85, and the center roller 95 are fixed to a sliding door panel.
However, as shown in FIG. 2, the center rail according to the prior art is configured of a linear part 94, a curved part 93, and an inwardly directed part 92. Here, since the inwardly directed part 92 and the curved part 93 are formed in a left and right direction of a vehicle, the center roller 95 moves in the left and right direction of the vehicle in the inwardly directed part 92 and the curved part 93. Therefore, when a user wants to open the sliding door, the user should pop up the sliding door while pushing the sliding door in the left and right direction and then slide the sliding door rearward.
However, in the center rail of the sliding door according to the prior art as described above, the curved part 93 excessively invades the interior of the vehicle to deteriorate dwelling ability. Moreover, since an operation direction of a handle and an opening or closing direction of the sliding door do not coincide with each other at the inwardly directed part and the curved part to disperse handle operation force, operability is deteriorated. Furthermore, since dispersion of a cross section of a curved bent part is large in a process of bending the curved part of the center rail, it is difficult to secure good quality.